firewire: fix website URL in Kconfig

The wiki in kernel.org is no longer updated. This commit replaces the
website URL with the latest one.

Link: https://lore.kernel.org/r/20240613090343.416198-1-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>